Or at least, a new idea to me. That's this idea of Gift Cards. I've known of gift vouchers forever of course, always used to get them myself when I was younger. But instead of your getting a voucher which you have to use all in one hit these newer gift cards work like a pre paid debit card to be used at a specific store.

So, granny can send near money but also know that it's going to get spent in a bookstore, rather than on alcohol or something more racy if she'd simply sent money. For example, they can supply the Apple Gift Card as well as those from a large number of other retailers.

There's a huge number of different options available for gift and credit cards at that link. Well worth checking out.